svn commit: r191674 - in head/sys/dev/ata: . chipsets

[Alexander Leidinger]

Quoting Alexander Motin <mav at FreeBSD.org> (from Wed, 29 Apr 2009  
21:17:18 +0000 (UTC)):

> Author: mav
> Date: Wed Apr 29 21:17:18 2009
> New Revision: 191674
> URL: http://svn.freebsd.org/changeset/base/191674
>
> Log:
>   Add experimental support for SATA interface power management.
>   Feature is controlled by hint.ata.X.pm_level tunable:
>    0 - PM disabled, old behaviour, default.
>    1 - device is allowed to initiate PM state change, host is passive.
>    2 - host initiates PARTIAL state transition every time port is idle.
>    3 - host initiates SLUMBER state transition every time port is idle.

Did I miss a man-page update for this? If yes, where is it, I would  
have expected it in ata(4).

>   PARTIAL state has up to 100us (50us for me) wakeup latency, but for my
>   ICH8M saves 0.5W of power per drive. SLUMBER state has up to 10ms (3.5ms
>   for me) wakeup latency, but saves 0.8W of power.
>
>   Modes 2 and 3 are implemented only for AHCI driver now.

Does this mean it is for SATA devices only, or is this a feature of  
the complete controller (ICH5 in my case) and also works with PATA  
drives?

Bye,
Alexander.

-- 
BOFH excuse #345:

Having to manually track the satellite

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